…ement

- Removed direct database interactions for audio job status updates and replaced them with calls to a new backend service.
- Introduced a backend client for fetching and updating audio job statuses asynchronously.
- Updated unit tests to reflect changes in the audio job processing logic, ensuring proper handling of job states (PENDING, PROCESSING, COMPLETED, FAILED).
- Deleted obsolete audio job model and repository files as they are no longer needed.

…rieval and processing

- Updated the audio generation service to fetch plan day and subtask data from the backend API instead of directly accessing the database.
- Refactored audio segment generation and timestamp handling to align with the new data structure.
- Introduced new backend client methods for audio job result application and payload retrieval.
- Improved unit tests to reflect changes in the audio generation logic and ensure proper integration with the backend services.

- Introduced `TestUploadDayAudio` to validate the key generation for uploaded audio files.
- Added `TestParseHelpers` class with tests for UUID parsing, audio type normalization, voice name handling, and result normalization.
- Enhanced existing tests for audio job processing to cover additional edge cases and error handling scenarios.